Effect of functional groups on the properties of multiwalled carbon nanotubes/polyvinylidenefluoride composite membranes

The development of advanced functional membranes with tailored properties is a key issue to be addressed in order to better exploit the potentialities of membrane-based separations processes. An important approach toward this aim is the realization of composite systems in which an organic and an inorganic phase coexist in order to have synergic effects on membrane properties. In this study functionalized multiwalled carbon nanotubes (MWCNT) and polyvinylidene fluoride (PVDF) are combined to produce composite porous membranes by solution casting and phase separation. The main goal is to gain more insight into the role of MWCNT functional groups on the interface-controlled properties of the composite films. The results show that the interactions between the polymeric matrix and the MWCNT are tailored by the nanotubes functionalization. In fact, Raman analysis support a better interaction of the PVDF polymer with the MWCNT functionalized with nitrogen containing groups (aminated and amidated) than with oxidized samples, thanks to the cooperative formation of hydrogen bonds and charge transfer complexes. The composite films, in particular that containing amidated MWCNT, show improved thermal, mechanic and transport properties in comparison with pure polymeric films.